This invention relates to a mold for molding a melted material into a wheel cover for a vehicle road wheel, the wheel cover being of the type having spoke-like portions integrally extending from a central portion to an annular radially outer peripheral portion.
For automobile road wheels, wheel covers having spokes or spoke-like portions are now in fashion. Since wheel covers having real spokes of metal wires, rods or tubes are costly and relatively heavy, a recent trend is to form a wheel cover having spoke-like portions or simulated spokes by injection molding of a synthetic resin or die casting of a light metal alloy.
When every spoke-like portion in a molded wheel cover extends in the direction of a radial line passing through the center of the wheel cover there is little problem in forming the spoke-like portions as part of a one-piece member. In some cases, the spoke-like portions are arranged slant with respect to the radii of the molded wheel cover as shown, for example, in U.S. Pat. Nos. 2,699,361, 4,275,930, 4,355,848 and 4,364,608 and U.K. Pat. No. 2,020,610. Besides such slanting, the spoke-like portions are usually oblique with respect to the center axis of the wheel cover because the central portion of the wheel cover projects axially outward from the annular radially outer peripheral portion. In a mold for molding such a wheel cover, the spoke-like portions are respectively formed in elongate grooves. It is natural that the mold surface in which the grooves are formed becomes a conically tapered surface because of the axially distant arrangement of the central portion and the radially outer peripheral portion of the wheel cover. Then there arises a problem. A seemingly linear groove formed slantwise in a conical surface is a curved groove in reality, as will be understood by considering three-dimensionally. Therefore, the slant spoke-portions of the molded wheel cover have an arcuate shape, whereas usually the spoke-like portions are desired to be straight.